Edi Santosa1 , Anas Dinurrohman Susila1 , Adolf Pieter Lontoh1, Arisa Noguchi2 , Ken Takahata2 , and Nobuo Sugiyama

  J. Agron. Indonesia 43 (3) : 257 - 263 (2015)

NPK Fertilizers for Elephant Foot Yam (Amorphophallus paeoniifolius

(Dennst.) Nicolson) Intercropped with Coffee Trees

_{1 1 1} Edi Santosa *, Anas Dinurrohman Susila , Adolf Pieter Lontoh , _{2 2 2 1} Arisa Noguchi , Ken Takahata , and Nobuo Sugiyama

  Department Agronomy and Horticulture, Faculty of Agriculture, Bogor Agricultural University ₂ Jl. Meranti, Kampus IPB Darmaga, Bogor 16168, Indonesia Faculty of Agriculture, Tokyo University of Agriculture, Funako, Atsugi, Kanagawa 243-0034, Japan

  Received 8 April 2015/Accepted 8 November 2015

  

ABSTRACT

Fertilizer application in elephant foot yams (Amorphophallus paeoniifolius (Dennst.) Nicolson) intercropping system

is rare in Indonesia, therefore, NPK fertilizers experiment was conducted under the shade of 10-year-old coffee plantation

at Leuwikopo Experimental Farm, Bogor, Indonesia, in order to increase the productivity of elephant foot yam intercropped

_-1

with coffee trees. Prior to planting, 20 ton ha of goat manure was applied. Four NPK combinations, i.e., N, P O , K O at the

• _-1
_{2 5 2}

rate of 0, 0 and 0; 100, 60 and 80; 125, 60 and 100; and 150, 60 and 120 kg ha , were applied. Results showed that there

were no significant differences in leaf number per plant, petiole size and rachis length among treatments. Application of NPK

decreased photosynthetic rates, while increasing rate of N and K O had no effect on photosynthetic rates. NPK application at

• _-1
₂

the 100 N, 60 P O and 80 K O kg ha (N P K treatment) or larger prolonged growth duration regardless of NPK levels,

_{2 5 2 100 60 80}

and there was a close relationship between corm yield and growth duration. As a result, corm fresh mass was higher in the

• _-1
• _-1

  100:60:80 kg ha treatment than in control. In the N P K and N P K kg ha treatments, leaves were damaged by

  _{125 60 100 150 60 120}

  heavy rains and winds, counteracting beneficial effect of NPK on growth duration and corm yield. These results suggested

  the importance of delay of entering dormancy for an increase in productivity of A. paeoniifolius. Keywords: NPK fertilizers, photosynthesis, productivity, prolong growth, tuber crop

  

ABSTRAK

Aplikasi pupuk jarang dilakukan pada tumpangsari suweg (Amorphophallus paeoniifolius (Dennst.) Nicolson) di

Indonesia, oleh karena itu, percobaan pemupukan NPK dilakukan di bawah naungan tanaman kopi umur 10 tahun di Kebun

  

Percobaan Leuwikopo, Bogor, Indonesia, untuk meningkatkan produktivitas tanaman suweg tumpangsari dengan kopi.

_-1

Sebelum tanam, pupuk kandang kambing diberikan sebanyak 20 ton ha . Percobaan menggunakan empat kombinasi pupuk

• _-1

  NPK yakni N, P O , K O sebanyak 0:0:0 sebagai kontrol, 100:60:80, 125:60:100 dan 150:60:120 kg ha . Hasil menunjukkan

_{2 5 2}

bahwa tidak ada perbedaan jumlah daun per tanaman, ukuran petiol dan panjang rachis antar perlakuan. Perlakuan NPK

nyata menurunkan laju fotosintesis, dan peningkatan dosis N dan K O tidak mempengaruhi laju fotosintesis. Perlakuan NPK

_{-1 2}

dosis 100 N, 60 P O and 80 K O kg ha (perlakuan N P K ) dan dosis di atasnya memperpanjang masa pertumbuhan.

_{2 5 2 100 60}

₈₀

Terdapat hubungan antara bobot umbi dengan lama masa pertumbuhan, yakni bobot segar umbi lebih besar pada tanaman _-1

dengan perlakuan 100:60:80 kg ha dibandingkan kontrol. Daun-daun mengalami kerusakan setelah ada hujan lebat dan

angin kencang, yang menghilangkan pengaruh perlakuan NPK terhadap lama masa pertumbuhan dan hasil umbi pada

_-1

perlakuan N P K dan N P K kg ha . Hasil penelitian menunjukkan perlunya menunda awal waktu dormansi dalam

_{125 60 100 150 60 120} upaya meningkatkan produktivitas tanaman umbi A. paeoniifolius.

  Katakunci: Fotosintesis, pertumbuhan, pupuk NPK, produktivitas, umbi-umbian

  INTRODUCTION corm contains a large amount of starch and a small amount of glucomannan, unlike most Amorphophallus species.

  Elephant foot yam (Amorphophallus paeoniifolius In India, elephant foot yam has been commercially (Dennst.) Nicolson, syn. Amorphophallus campanulatus cultivated (Srinivas and Ramanathan, 2005). In Indonesia, (Roxb.) BL. ex Dence) is a native tuberous crop in South on the other hand, elephant foot yam is an underutilized Asia (Sugiyama and Santosa, 2008; Ravi et al., 2009). Its crop that commonly grows under shading (Sugiyama and

  Santosa, 2008). Until 1960s, elephant foot yams had been used as a staple food during the off-season of rice in Central Java. Since the 1960s, the ‘Green Revolution’ boosted

• Corresponding author. e-mail:edisang@gmail.com NPK Fertilizers for Elephant......

MATERIALS AND METHODS

  layer. Sumarwoto (2005) reported that application of P ₂ O ₅ and K ₂ O do not affect growth of A. muelleri under the canopy of Albizia falcataria. Santosa et al. (2006) reported that productivity of A. paeoniifolius growing under 75% shading nets is larger than in 0% shading. Meaning that fertilizers at higher rates is likely required in shading condition than application on the productivity of A. paeoniifolius in coffee plantation.

  A C A B D C C D C

  

Figure 1. A. paeoniifolius plants intercropped with coffee trees in Bogor, Indonesia. (A) Condition of plants at 4 weeks after planting

(WAP); (B) A. paeoniifolius at 12 WAP; (C) Plant height at maximum vegetative phase (20 WAP); (D) Some plants showed leaf collapse at 18 WAP in the N ₁₅₀ P ₆₀ K ₁₂₀ treatment

  The plots were arranged in completely randomized block design with three replicates. Each plot consisted of one bed (1 m wide and 10 m long) where 15 whole corms with about 1 cm bud were planted in a triangle distance of

  Whole one-year-old corms were planted on August 8, 2010. Average seed corm weight was 396 ± 92 g with a diameter of 9 ± 1 cm. Corms were collected from a farmer’s field in Kulonprogo, Yogyakarta. According to the farmer’s information, the harvested corms were derived from plants without any fertilizer, except for natural tree litter on the farm.

  ). Soil texture was clay (sand:silt:clay = 13.1:22.1:64.8%). Air temperature during experiment was 23 to 32 ºC (25.6 ºC on average) with relative humidity 85-88 %.

  6 m between the rows and 4 m in the rows in 1994 (Figure 1). By regular pruning, the canopy of coffee tree was maintained at the height of 4-5 m and width of 4.5 m on average. Average light intensity was reduced by 40% of full sunlight. The soil had pH 5.2, and contained a low amount of total N (0.12% by Kjeldahl method), very low amount of Bray I phosphorus (5.9 mg kg

• ^-1 ) and low amount of exchangeable potassium (26 me 100 g ^-1

  robusta) were planted in Latosol Darmaga type at a distance

  The experiment was conducted at Leuwikopo Experimental Farm of IPB, Darmaga (260 m above sea level) from August 2010 to May 2011. Coffee trees (Coffea

  258

  Edi Santosa, Anas Dinurrohman Susila, Adolf Pieter Lontoh, Arisa Noguchi, Ken Takahata, and Nobuo Sugiyama J. Agron. Indonesia 43 (3) : 257 - 263 (2015)

  types. Mondal et al. (2012) recommend applying 10 tons manure per hectare for high quality A. paeoniifolius crops. However, there are few studies on the effect of fertilizer on A. paeoniifolius growth under the shade of plantation trees. Singh et al. (2013) stated that the bitter gourd can be profitably grown with A. paeniifolius under multilayer vegetable cropping system, although the corm yield of A.

   dependent on soil

  N and K are important nutrients to increase corm yield of Amorphophallus species (Sugiyama and Santosa, 2008; Ravi et al., 2009; Santosa et al., 2011). Ravi et al. (2009) recommends application of N at levels of 50 to 200 kg ha

• ^-1 and K
₂ O at level of 75 to 150 kg ha ^-1

  to bad agricultural practices such as no fertilizer application (Sugiyama and Santosa, 2008).

  paeoniifollius in the field is low in Indonesia, possibly due

  102.3 ton ha ^-1 with N application at level of 50 kg ha ^-1 and 150 kg ha

• ^-1 , respectively. However, the productivity of A.

  densely distributed in Java, and is also found in some places of Sumatra, Bali, Lombok and Sulawesi islands (Sugiyama et al., 2010). Ravi et al. (2009) reported that the corm yield of elephant foot yams is 84.6 ton ha

• ^-1 and

  A. paeoniifolius locally called suweg is widely and

  elephant foot yam. However, steamed corms are still used in some districts of Java (Sugiyama and Santosa, 2008).

  paeniifolius was reduced by about 10% under bitter gourd

RESULTS AND DISCUSSION

  al. (2011) have reported that N and K applications increase petiole length. Photosynthetic Rate

  Senescent leaves (yellowing leaves) were not included in leaf number. Leaf number larger than one means the coexistence of leaves; _Y Mean ± S.E; different letters indicate statistical differences within columns; ^Z no leaf

  Table 1. Temporal changes in leaf number of A. paeoniifolius plants grown with different levels of NPK fertilizers ^X X

  N ₁₂₅ P ₆₀ K ₁₀₀ 1.9±0.4a 1.9±0.4ab 1.7±0.2b 1.7±0.2b 1.8±0.3a 0.9±0.2a 0.3±0.2a N ₁₅₀ P ₆₀ K ₁₂₅ 1.6±0.2b 1.8±0.0b 1.7±0.1b 1.7±0.1b 1.5±0.1a 0.6±0.0a 0.2±0.2a

  8 No NPK 1.5±0.2b ^Y 1.8±0.3ab 1.7±0.2b 1.7±0.2b 1.6±0.2a 0.7±0.1a - ^Z N ₁₀₀ P ₆₀ K ₈₀ 1.6±0.1b 2.1±0.1a 2.0±0.0a 2.0±0.0a 1.7±0.3a 0.9±0.4a 0.2±0.2a

  7

  6

  5

  4

  3

  2

  Times after planting (months)

  under coffee trees during the sunny days. At this range NPK treatment

  Photosynthetic rates increased with an increase in photosynthetic active radiation (PAR) in any treatment (Figure 2). PAR ranged from 500 to 1,000 Pmol photon m

• ^-2 s ^-1

  NPK Fertilizers for Elephant......

  J. Agron. Indonesia 43 (3) : 257 - 263 (2015)

  Leaf Size

  P ₆₀ K ₁₀₀ and N ₁₅₀ P ₆₀ K ₁₀₀ treatments (Table 2). Occurrence of leaf collapse increased thereafter in all treatments.

  From 10 WAP to 20 WAP (September to December 2010), monthly rainfall ranged from 178 to 601 mm. On November 10, 2010, there was heavy rain (50 mm day ^-1 ) and wind up to 43 km h

• ^-1 . As a result, leaf number decreased at 4 MAP due to leaf collapse at 14 WAP in the N ₁₂₅

  significantly delayed harvesting time and increased number of leaves.

  et al. (2013) that in A. muelleri, application of KNO ₃

  First leaf emerged 2 to 4 weeks after planting (WAP), irrespective of NPK treatments. During vegetative growth, plants in all treatments generated more than one leaf from 2 to 6 months after planting (MAP) (Table 1). At 2 MAP, leaf number was significantly larger in the N ₁₂₅ P ₆₀ K ₁₀₀ treatment than in others, but there were no significant differences in leaf number among treatments from 6 MAP and onward (Table 1). This in the contrary with the result of Santosa

  Leaf Number

  Daughter corm size and weight were measured. Corms were peeled, sliced, then oven dried at 120 ^o C for three days for the measurement of dry matter content. Statistical analysis was performed using ANOVA, and mean separation was carried out by Tukey's range test. A chi-square ( F ) test was performed to test the fit between a theoretical frequency distribution and a frequency distribution of observed data on corm size and time to dormancy. Analysis of covariance was lines.

  Watering was applied every three days, if rainfall was less than 20 mm per day each for three consecutive days. Hand weeding was carried out twice a month. Pesticides, i.e., 2% diazinon and 2% mancozeb were mixed and applied monthly at rate 400 L ha

• ^-1 . Plant growth characters, i.e., number of leaves, petiole size, canopy size, photosynthetic rates and time to dormancy, were measured for five plants planted in the center of the beds. Petiole height was measured from 3 cm above soil level to the joint of tripartite rachis. Canopy size was determined by measuring the horizontal distance between the tips of a tripartite leaf and petiole. Photosynthetic rate was measured on February 15, 2011 (at the peak vegetative stage) using LICOR 6400 XT Portable Photosynthetic System. Harvest was carried out after all plants had entered dormancy (May 15, 2011). Dormancy was determined based on complete senescence of leaves.

  Prior to planting, corms were immersed to 2% solution of mancozeb. Rice husk was spread out to achieve a thickness of 10 cm at the planting hole. Seed corms were planted with bud face up and planted 10 cm below soil surface. NPK was applied twice; one month after planting at which time bud reached about 15 cm, and two months after planting at which time the first leaf had fully expand. At planting, about 2 g of 3% carbofuran was applied on the cavity of bud. Soil was regularly raised every month. Prior to harvest, daughter corm position was marked by putting stick close to plants.

  N, P ₂ O ₅ and K ₂ O sources were urea (46% N), SP-36 (36% P ₂ O ₅ ), and KCl (60% K ₂ O), respectively.

  (N ₁₂₅ P ₆₀ K ₁₀₀ ); and 150, 60 and 120 kg ha ^-1 (N ₁₅₀ P ₆₀ K ₁₂₀ ).

  up to a depth of 30 cm using tractor, one month prior to planting. Two weeks prior to planting, goat manure of about 1 kg (equal to 20 ton ha ^-1 ) was applied in planting hole (25 cm × 25 cm in a depth of 20 cm). Four combinations of N, P ₂ O ₅ and K ₂ O were applied at the rate of 0, 0 and 0 (N P K ); 100, 60 and 80 (N ₁₀₀ P ₆₀ K ₈₀ ); 125, 60 and 100

  There were no significant differences in petiole size (length and diamater) and rachis length of both the first and the second leaves among treatments (Table 3). Furthermore, there were no significant differences in canopy size and life span of the first and the second leaves among treatments, although NPK application slightly increased the canopy size and life span of the second leaf (Table 4). In line with this result, Sugiyama and Santosa (2008), and Santosa et

  J. Agron. Indonesia 43 (3) : 257 - 263 (2015) _W

  Time (weeks after planting) NPK treatment _Z

  10 _{X Y}

  14

  18

  22

  26 No NPK - 6±3b 31±10ab 52±2b 53±3b _{100 60 80} - N P K 4±2b 28±1b 54±7ab 54±7ab N P K 3±3 28±11a 41±5a 66±9a 69±9a _{125 60 100 W} N - P K 17±6a 41±4a 68±8a 73±6a _{150 60 125}

  

Incidence of leaf collapse was judged whether or not petiole was bent down and damaged. Senescent leaf was excluded for the judgment

_{X Y Z}

of leaf collapse; no incidence of leaf collapse; Mean ± S.E; different letters indicate statistical differences within columns; F value of

4.17 in ANOVA on data at 14 WAP indicates significant differences within a column at P = 0.10

  Table 3. Petiole size of the first and the second leaves (cm) of A. paeoniifolius grown with different levels of NPK fertilizers _W First leaf Second leaf

  NPK treatment _{X Y} Petiole length Petiole diameter Rachis length Petiole length Petiole diameter Rachis length _Z

  No NPK 83.2±12.3a 3.0±0.4a 62.2±10.5a 96.8±6.4a 3.1±0.0b 59.7±1.5b N P K 87.8±13.3a 3.1±0.5a 65.1±9.1a 116.4±13.6a 3.9±0.3a 70.7±5.8a _{100 60 80} N P K 84.6±15.6a 3.3±0.6a 64.9±11.5a 101.5± 9.5a 3.8±0.1a 67.9±2.3a _{125 60 100 W} N P K 84.8±14.4a 3.2±0.7a 63.7±12.4a 110.7±14.0a 3.7±0.5a 71.1±8.5a _{150 60 125 X Y Z}

A leaf which first emerges from corm; Measured from soil surface to a tripartite branch of rachis; Measured at 5 cm above soil surface;

Mean ± S.E ; different letters indicate statistical differences within columns

  Table 4. Number of leaflets, canopy width and life span of the first and the second leaves of A. paeoniifolius grown with different levels of NPK fertilizers _W First leaf Second leaf

  NPK treatment _{X 2 Y 2} Canopy size (m ) Life span (weeks) Canopy size (m ) Life span (weeks) _Z No NPK 1.1±0.3a 16.7±0.7a 1.0±0.1a 21.2±0.7a N P K 1.2±0.2a 16.7±0.2a 1.4±0.3a 23.6±1.4a _{100 60 80} N P K 1.1±0.4a 16.5±0.3a 1.3±0.1a 22.5±3.3a _{125 60 100}

  N P K 1.1±0.4a 16.3±0.3a 1.4±0.3a 22.8±2.0a _{W 150 60 125 X Y}

  

A leaf which first emerges from corm; Estimated from canopy length and width at the maximum leaf expansion; Weeks from emergence

_Z to senescence of leaves; Mean ± S.E; different letters indicate statistical differences within columns

  of PAR, photosynthetic rate was 108 to 173 Pmol CO yam increases after triazole (paclobutrazol) application due _{-2 -1 -2 -1 2} m s with an average of 130 Pmol CO m s . Stomatal to increasing in chlorophyll and carotenoid contents. _{2 -2 -1} conductance ranged from 0.005 to 0.024 mol CO m s

• _{-2 -1}
₂ with an average of 0.019 mol CO m s . Daughter Corm ₂ Photosynthetic rates were significantly higher in control than in NPK treatments at a PAR of 1,000 Pmol Regarding with the time to dormancy, there were
• _{-2 -1} photon m s or higher, but there were no significant no significant differences among treatments (Table 5), differences in photosynthetic rates among three NPK but a large variation was found among plants within the treatments, regardless of light intensity (Figure 2). It is same treatments (Table 6). When chi-square ( F ) test was considered that actual photosynthetic rates in control plants performed using data on the time to dormancy and corm were almost the same as those in NPK treatments in this size in the N P K treatment and control, the frequency ₁₀₀
_{60 80} study because PAR ranged between 500 and 1,000 Pmol distribution were significantly different between two
• _{-2 -1} photon m s under the canopy of coffee trees. This might treatments; the N P K treatment increased the percentage ₁₀₀
_{60 80} be the reason why there were no differences in leaf size and of corms entering dormancy at 28 WAP or later (Table 6) leaf number among the treatments (Table 1). Gopi et al. and also the percentage of corms heavier than 1,000 g as (2009) stated that net photosynthetic rate of elephant foot compared to control plants (Table 7).

  Edi Santosa, Anas Dinurrohman Susila, Adolf Pieter Lontoh, Arisa Noguchi, Ken Takahata, and Nobuo Sugiyama

  260

  J. Agron. Indonesia 43 (3) : 257 - 263 (2015) _{2 2 2} A

  B. y = 0.00003x + 0.001x + 106.7

  A. y = 0.00005x + 0.006x + 109.7

  B. y =

  B. y = 0.00003x + 0.001x + 106.7 0.00005x + 0.006x + 109.7 y = 0.00003x + 0.001x + 106.7 B R² = 0.953

  R² = 0.991 R² = 0.953 R² = 0.991 R² = 0.953 C 200

• _-1 )

  D _-2 s m l

  150 mo 

      ( e at r n o

  100 ti la mi ssi _{2 2} A

  C. y = 0.000006x + 0.047x + 92.56 0.000006x + 0.047x + 92.56 D. y = 0.00005x - 0.009x + 104.0

  50 R² = 0.975 R² = 0.975 R² = 0.996 R² = 0.996 250 500 750 1000 1250 1500

• _{-2 -1}  PAR ( mol m s )    

  Figure 2. Photosynthetic rates of A. paeoniifolius P K grown with different levels of NPK fertilizers. A, No NPK (◊); B, N (□); C, _{100 60 80} N P K P K (x) treatments. Measurements were carried out three times for a leaf, without respect of leaf _{125 60 100 150} (∆); and D, N _{60 125} number

  Table 5. Yield of elephant foot yams grown with different level of NPK fertilizers _X Corm size Cormel Time to dormancy

  Treatment _{Y Z} Weight (g) Diameter (cm) Height (cm) Number Weight (g) (WAP )

  No NPK 726±19b 12.0±0.2a 6.6±0.2c 19.6±5.3a 166.3±52.4a 26.6±0.7a N P K 1,324±157a 13.9±0.8a 8.1±0.5a 26.0±3.6a 308.0±77.4a 29.0±0.7a _{100 60 80} N P K 917±24b 12.4±0.2a 7.3±0.2b 21.7±5.8a 198.7±69.4a 27.8±1.2a _{125 60 100 X Y Z} N P K 889±264b 12.3±1.6a 7.3±0.9abc 23.5±3.7a 194.3±46.1a 28.3±1.4a _{150 60 125}

  

Cormels larger than 0.5 cm in length were measured; Fresh mass of corm without cormels; Average week after planting; Mean ± S.E;

followed by different letters indicate statistical differences within columns

  Table 6. Percentage of corms which were categorized into four classes by the time to dormancy (weeks) _X Time to dormancy (Weeks) NPK treatment

  20-24 24-28 28-32 >32 No NPK

  26.7

  26.7

  46.6

  0.0 N P K _{100 60 80}

  0.0

  33.3

  60.0

  6.7 N P K _{125 60 100}

  13.3

  26.7

  60.0

  0.0 _X N P K _{150 60 125}

  6.7

  20.0

  73.3

  0.0

  value was 7.84 (P<0.05, d.f.=3) when test was performed using frequent distribution data of corm weight in the N P K treatment

  F F _{100 60 80}

  control

  Analysis of covariance indicated that there were no of A. paeoniifolius was dependent on growth duration, not differences in the slopes of the regression lines whether on the levels of NPK fertilizers (Figure 3). In the N P K _{125 60 100} regressions were calculated for each treatment data or and N P K treatments, a high incidence of leaf collapse _{150 60 125} for combined data. Figure 3 which was obtained using decreased the percentage of corms which were harvested combined data indicated that fresh mass of corms linearly later than 32 weeks, resulting in low corm weight in the increased with a delay of harvest. This suggests that yield N P K and N P K treatments. Saikia and Borah _{125 60 100 150 60 125} NPK Fertilizers for Elephant......

  J. Agron. Indonesia 43 (3) : 257 - 263 (2015)

  leaf, thick petiole, heavy corms and prolonged growth duration and yield of A. paeoniifolius increased by the _-1 duration in A. paeoniifolius, as compared with late planting. application of NPK in addition to 20 ton ha manure, but N, This is similar to the present experiment in that prolonged P O , and K O applications at the rate higher than 100 kg, _{2 5 2 -1} growth period increased yield. Therefore, it is likely that N, 60 kg and 80 kg ha , respectively, did not show any effect

  P O , and K O applications at the rate of 100 kg, 60 kg and on growth duration and yield. This detrimental finding is _{2 5 -1 2} 80 kg ha , respectively, prolongs growth period possibly likely coincident with collapse leaves due to heavy rainfall due to the delay in entering dormancy, leading to larger fresh and winds. Santosa et al. (2013) stated that application masses of corms. It is possible that NPK fertilizer could of KNO at the level of 4% favors plant growth and yield ₃ enhance root function in absorbing water for a long time. when it is applied through foliar than soil application in A.

  Santosa et al. (2004) reported that A. paeoniifolius growing muelleri. Meaning that, collapse leaves resulted in reduction in a greenhouse enters dormancy earlier under limited water ability of A. paeoniifolius to conduct photosynthesis and to supply than under sufficient water supply. utilize nutrients. _z Table 7. Percentage of corms which were categorized into five classes by corm weight (g) _z

  Categories of corm weight (%) NPK treatment

  <500 g 501-1,000 g 1,001-1,500 g 1,501-2,000 g >2,000 g No NPK

  20.0

  66.7

  13.3

  0.0

  0.0 N P K _{100 60 80}

  6.7

  33.3

  26.7

  20.0

  13.3 N P K _{125 60 100}

  13.3

  46.7

  26.7

  6.7

  6.7 _Z N P K _{150 60 125}

  20.0

  40.0

  26.7

  6.7

  6.7

  value was 12.95 (P<0.05, d.f.=4) when test was performed using frequent distribution data of corm weight in the N P K treatment

  F F _{100 60 80}

  control 3000

  ) g Y=122.6x-2459.5 ₂ (R =0.475) rms ( co f o

  2000 mass sh re F

  1000

  20

  25

  30

  35 Time to harvest (weeks)

Figure 3. Correlation between corm fresh mass and time to harvest of A. paeoniifolius grown with different levels of NPK fertilizers. A, No

P K P K P K (

  NPK (●); B, N (○); C, N (▲); and D, N _{100 60 80 125 60 100 150 60 125} △) _-1 CONCLUSION size. NPK treatment of 100:60:80 kg ha produced largest

  corm fresh mass than those of other treatments. Therefore, NPK application prolonged growth duration, but did it seems necessary to elucidate the cultural practices for not increase photosynthetic rate. Growth duration changed lengthening growth duration to get higher yield. even in the same treatment, causing a large variation in corm

  Edi Santosa, Anas Dinurrohman Susila, Adolf Pieter Lontoh, Arisa Noguchi, Ken Takahata, and Nobuo Sugiyama

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  NPK Fertilizers for Elephant......

  Nitrogen and potassium applications on growth of

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  Thanks to Mr Haryanto and Mr Joko Mulyono for assisting data collection in the field and laboratory works. This collaborative study between Bogor Agricultural University, Indonesia and Tokyo University of Agriculture, Japan was fully supported by the Incentive Grant No RT- 2010-0864 and RT-2011-2608 from Ministry of Research and Technology (Menristek), Republic of Indonesia.

  Biodivertas 6:185-190.